Retirement Benefit Plans (Schedule of Changes in Plan Assets, Changes in Projected Benefit Obligation, Rate Assumptions, and Components of Net Periodic Benefit Costs) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Change in fair value of plan assets
Fair value of plan assets at end of year	$ 26,337	$ 25,274
Pension Plans, Defined Benefit
Change in projected benefit obligation
Benefit obligation at beginning of year	27,812	31,709
Service cost	12	16
Interest cost	1,274	1,131
Liability actuarial loss (gain)	4,352	(3,680)
Benefits paid	(1,399)	(1,364)
Benefit obligation at end of year	32,051	27,812
Change in fair value of plan assets
Fair value of plan assets at beginning of year	25,274	21,838
Return on plan assets	1,262	3,226
Employer contributions	1,200	1,574
Benefits paid	(1,399)	(1,364)
Fair value of plan assets at end of year	26,337	25,274
Underfunded status – December 31, 2014	(5,714)	(2,538)
Supplemental Employee Retirement Plans, Defined Benefit
Change in projected benefit obligation
Benefit obligation at beginning of year	3,021	3,057
Service cost	152	114
Interest cost	138	102
Liability actuarial loss (gain)	421	(252)
Plan amendments	0	0
Benefit obligation at end of year	3,732	3,021
Hourly Employees’ Pension Plan \| Pension Plans, Defined Benefit
Change in projected benefit obligation
Benefit obligation at beginning of year	9,477	10,786
Service cost	8	11
Interest cost	422	371
Liability actuarial loss (gain)	1,189	(1,060)
Benefits paid	(640)	(631)
Benefit obligation at end of year	10,456	9,477
Change in fair value of plan assets
Fair value of plan assets at beginning of year	8,873	7,690
Return on plan assets	442	1,136
Employer contributions	548	678
Benefits paid	(640)	(631)
Fair value of plan assets at end of year	9,223	8,873
Underfunded status – December 31, 2014	(1,233)	(604)
Employees’ Retirement Plan \| Pension Plans, Defined Benefit
Change in projected benefit obligation
Benefit obligation at beginning of year	18,335	20,923
Service cost	4	5
Interest cost	852	760
Liability actuarial loss (gain)	3,163	(2,620)
Benefits paid	(759)	(733)
Benefit obligation at end of year	21,595	18,335
Change in fair value of plan assets
Fair value of plan assets at beginning of year	16,401	14,148
Return on plan assets	820	2,090
Employer contributions	652	896
Benefits paid	(759)	(733)
Fair value of plan assets at end of year	17,114	16,401
Underfunded status – December 31, 2014	$ (4,481)	$ (1,934)

Retirement Benefit Plans (Schedule of Changes in Plan Assets, Changes in Projected Benefit Obligation, Rate Assumptions, and Components of Net Periodic Benefit Costs) (Details) (USD $)
In Thousands, unless otherwise specified